In design and manufacturing of a product, the performance and life expectancy have played a crucial role in what components are selected along with their reliability characteristics. Since most products have an eventual customer that will be using the product, the overall reliability of product is often based on customer needs, market expectation, or other similar based measures of end user reliability standards. Often, a manufacturer will desire to test the given product so a manufacturing reliability level is set to perform production acceptance testing of the product.
Once a particular goal is set then the individual sub-system and component reliability levels are set to meet the overall design goal. These reliability criteria are designed to allow for selection of the sub-systems or components based on criteria that will allow the design to perform to specification. However, the actual customer usually does not get the same level of performance as the design criteria suggested. This is caused by various sources during the product life cycle that occur after the selection of sub-systems or components.
The product life cycle downstream of the selection of the sub-systems or components is often affected by additional losses of performance. Some of these losses include skill level used in the manufacturing of the final product and other organizational constraints during manufacturing. Other downstream areas that can be considered are installation, warranty service, customer use (including misuse and/or abuse), and planned or unplanned maintenance. These factors typically play a larger role in the measured and perceived reliability for repairable systems than system design parameters. Such factors, however, are not taken into account when setting overall system reliability goals. Therefore, there remains a need for improvement of the setting of reliability targets of a product based on actual customer experiences and expectations.